[vlc-devel] [vlc-commits] Lua: convert playlist parser back to demux

[Rémi Denis-Courmont]

Le keskiviikkona 30. syyskuuta 2020, 8.12.18 EEST Steve Lhomme a écrit :
> On 2020-09-29 17:07, Rémi Denis-Courmont wrote:
> > Le tiistaina 29. syyskuuta 2020, 8.21.59 EEST Pierre Ynard via vlc-devel a
> > 
> > écrit :
> >>> Lua: convert playlist parser back to demux
> >> 
> >> So this means that neither ytdl nor lua playlist parsers are getting
> >> auto-probed anymore by vlc_stream_NewURL(),
> > 
> > Yes.
> 
> This seems like making it impossible for the Lua stream filters

Err, the whole point is to not parse playlists in stream filters.
Thomas pointed out that it was too damn slow.

And then there's the Trac ticket that Pierre referenced.

> to return a different content than the original stream,

We stopped doing that sort of hacks years ago when we introduced pf_readdir 
and converted the directory access.

I wouldn't go as far as Pierre's objection to synthetic bitstreams on IPC 
interfaces (as in the some unmerged versions of the YoutubeDL plugin), but I 
agree with him that it's poor design within process.

> This is not just for Lua scripts. The ytdl module should also do the
> same rather than force one version of the stream regardless of
> network/screen/gpu capabilities.

The YoutubeDL plugin should not be a stream filter for the exact same 
performance and hijack reasons as Lua. Distinct muxers per-ES are possible 
regardless. They just needs a lot of boilerplate code, and implies that the 
muxers all support accurate seeking.

However adaptive ES's are not currently possible. On one hand, the demux 
controls are geared for pretty much exclusively MPEG-TS. On the other hand, 
there are no ways to propagate the video rendering size back up to the 
demuxer. Both challenges are core design limitations.

-- 
Rémi Denis-Courmont
http://www.remlab.net/